Παραπομπή APA
World Tourism Organization. (2002). Voluntary initiatives for sustainable tourism: Worlwide inventory and comparative and comparative analysis of 104 eco-labels, awards and self-commitments. Madrid, Spain: World Tourism Organization.
Παραπομπή Chicago StyleWorld Tourism Organization. Voluntary Initiatives for Sustainable Tourism: Worlwide Inventory and Comparative and Comparative Analysis of 104 Eco-labels, Awards and Self-commitments. Madrid, Spain: World Tourism Organization, 2002.
Παραπομπή MLAWorld Tourism Organization. Voluntary Initiatives for Sustainable Tourism: Worlwide Inventory and Comparative and Comparative Analysis of 104 Eco-labels, Awards and Self-commitments. Madrid, Spain: World Tourism Organization, 2002.
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